Motor fuel composition

ABSTRACT

Motor fuel composition comprising a mixture of hydrocarbons in the gasoline boiling range containing 0.03 to 1.0 volume percent of a paraffinic oil fraction consisting of at least 55 percent of paraffinic hydrocarbons and less than 16 percent of aromatic hydrocarbons and having an average molecular weight in the range from 540 to 850, and method of preventing a deposits build-up in a gasoline engine.

Moore et al.

[ 1 MOTOR FUEL COMPOSITION [75] V Inventors: Fred W. Moore, Fishkill;Herbert E.

Vermillion, Wappingers Falls, both of N.Y.

[73] Assignee: Texaco Inc., New York, NY,

[22] Filed: Mar. 6, 1969 [21] Appl. No.: 804,978

[52] US. Cl. 44/58 [51] Int. Cl C101 1/10 [58] Field of Search 44/58[56] References Cited UNITED STATES PATENTS 2,965,458 12/1960 Sawyer eta1. 44/58 3,020,134 2/1962 Keller et a1. 44/58 3,031,278 4/1962 Buckmannet a1 44/58 3,035,905 5/1962 Keller 44/58 3,235,494 2/1966 Piatt et a1.44/58 X Apr. 15, 1975 3,326,801 6/1967 SChlObOhm et al. 44/58 X3,751,235 3/1973 Schoen 44/58 FOREIGN PATENTS OR APPLICATIONS 683,19711/1952 United Kingdom 44/58 Primary Examiner-Winston A. DouglasAssistant Examiner-W. J. Shine Attorney, Agent, or FirmT. H. Whaley; C.G. Ries [57] ABSTRACT Motor fuel composition comprising a mixture ofhydrocarbons in the gasoline boiling range containing 0.03 to 1.0 volumepercent of a paraffinic oil fraction consisting of at least 55 percentof paraffinic hydrocarbons and less than 16 percent of aromatichydrocarbons and having an average molecular weight in the range from540 to 850, and method of preventing a deposits build-up in a gasolineengine.

8 Claims, No Drawings MOTOR FUEL COMPOSITION This invention relates to amotor fuel composition for a four-cycle, spark-ignited internalcombustion engine. More particularly, the invention relates to a motorfuel composition containing a selected high-boiling mineral oil fractionin an amount effective to reduce or eliminate the formation of harmfuldeposits on the intake valves and around the intake ports of an internalcombustion engine.

Internal combustion engines, particularly of the overhead valve design,are subject to a substantial build-up of hard, tenacious deposits on theintake valves and ports of the engine. These deposits interfere with theoperation of the fuel intake system. As the deposits level grows, theengine exhibits loss of power, rough idling and, occasionally, valveburning. When the deposits become excessive, portions break off and aredrawn into the combustion chamber. Instances of mechanical damage to thepiston and piston rings caused by these deposits have been observed.

Considerable work has been conducted to determine the nature and causeof the intake valve deposits. The deposits themselves are composedessentially of the byproducts of fuel combustion and lubricating oildeterioration. Analysis of the deposits indicates that the viscosityindex improvers contained in the lubricating oil act as binders for thedeposits. Polymethacrylate viscosity index improvers, as an example, areone'class of materials which appear to contribute materially to thedeposits build-up.

An understanding of engine operation will show how lubricating oildeterioration can contribute to deposits in the fuel intake system. Aspark-ignited internal combustion engine contains a reservoir oflubricating oil in the crankcase. When the engine is in operation. thegreater part of the crankcase oil is splashed up on the operating partsof the engine and on the cylinder walls. A portion of this oil, however,is pumped under pressure to the upper parts of the engine to lubricatethe working parts therein. In an overhead valve engine, a small streamof the oil pumped to the upper section of the engine is constantly rundown the intake and exhaust valve stems to insure that they areconstantly lubricated in their guides during operation. The oiltrickling down the intake valve stem, the valve head and around theintake port is apparently pyrolyzed under the temperatures prevailing,thereby contributing to the formation and build-up of the above-noteddeposits.

This particular problem is not encountered to any material extent in theexhaust mmanifold or around the exhaust ports or valves. This isbelieved to be due to the high temperatures existing in the exhaustmanifold and to the action of the expelled exhaust gases which do notpermit the laydown of deposits or continually burns and carries off anypotential deposits.

Gasolines containing a minor amount of a distillate mineral oil as anupper cylinder lubricant or top oiler" are well known. In general, theupper cylinder lubricants employed in gasoline have been lightdistillate mineral oils as opposed to heavier lubricating oil fractions.Indeed, the latter have generally been found to be harmful from theviewpoint of deposit formation in the combustion chamber. A top cylinderlubricating oil commercially employed in a premium gasoline ischaracterized as a highly refined distillate lubricating oil fractionhaving an average molecular weight of about 300 and a 50 percentdistillation point of about 700F.

It has now been discovered that a minor amount of certain highlyrefined, high boiling, paraffinic lubricating oil fractions dissolved ina motor fuel composition is effective for preventing the formation ofdeposits on the intake valves and ports of a four-cycle, sparkignited,internal combustion engine. More specifically, a motor fuel compositioncomprising a mixture of hydrocarbons boiling in the gasoline boilingrange containing from about 0.03 to [.0 volume percent ofa paraffinicmineral oil fraction consisting of at least 55 percent of paraffinichydrocarbons and less than 16 percent of aromatic hydrocarbons andhaving an average molecular weight in the range from 540 to 850 iseffective for preventing the aforesaid deposits. These oil fractions canalso be characterized by their 50 percent distillation point which is ata temperature of at least 940F. or higher.

Average molecular weight as employed herein refers to molecular weightdetermination by the ASTM Osmometer Method under ASTM number D250367.

The nature of the mineral oil fraction effective to provide a gasolinecomposition having the property of preventing intake valve and portdeposits in a gasoline engine is critical. In general, only a refinedparaffinic mineral oil fraction of lubricating oil quality consisting ofat least 55 percent and up to 100 percent paraffinic hydrocarbons andless than 16 percent of aromatic hydrocarbons, the fraction having anaverage molecular weight in the range 540 to 850 is effective for thepurpose described. The preferred oils are those consisting of 60 to 100percent paraffinic hydrocarbons and less than 7 percent of aromatichydrocarbons having an average molecular weight in the range of 600 to800. Particularly preferred oils are those consisting of 60 to percentof paraffinic hydrocarbons and less than 7 percent aromatichydrocarbons. These oil fractions characteristically have a.50 percentdistillation point of at least 940F. or higher and, more specifically,in the range of 950 to l lOOF.

Light lubricating oil fractions having molecular weights below thecritical range are ineffective in this invention. These ineffective oilsalso have a 50 percent distillation pointbelow about 875F.Non-paraffinic lubricating oil fractions are also ineffective in thisinvention and, in addition, result in prohibitively high depositsformation in the combustion chamber of the car engme.

The base fuel of the invention comprises a mixture of hydrocarbonsboiling in the gasoline boiling range. This base fuel may consist ofstraight chain or branched chain paraffins, cyclo-paraffins, olefins andaromatic hydrocarbons or any mixture of these. This fuel can be derivedfrom straight run naphtha, polymer gasoline, natural gasoline or fromcatalytically cracked or thermally cracked hydrocarbons andcatalytically reformed stocks. The composition of the base fuel is notcritical nor does the octane level of the base fuel have any materialeffect on the invention. Any conventional motor fuel base may beemployed in the practice of this invention.

The base fuel may contain any of the additives normally employed in amotor fuel. For example, the base fuel may contain an anti-knockcompound, such as a tetraalkyllead compound including tetraethyllead,tetramethyllead, tetrabutyllead, mixtures thereof and the like. Thetetraalkyllead mixture commercially available for automotive usecontains an ethylene chlorideethylene bromide mixture as a scavenger forremoving lead from the combustion chamber in the form of a volatile leadhalide. The tetraalkyllead mixtures are generally employed in gasolinein a concentration ranging from about 0.5 to 4.0 cc. of the mixture pergallon of gasoline. Other conventional additives for this gasoline,including anti-icing agents, corrosion inhibitors, dyes, carburetordetergents, deposit modifiers, multipurpose additives and the like, areillustrated by the following US Pat. No. 2,632,695, 2,844,449,3,325,260, 3,232,724, 2,622,018 and 2,922,708.

The novel fuel composition of the invention is prepared by mixing asuitable amount of a suitable paraffinic mineral oil fraction to thebase gasoline. The minimum amount of additive employed in the fuelcomposition is critical in order to realize the benefits of theinvention. Broadly, the additive must be employed in a range from about0.03 to 1.0 volume percent. Highly effective results have been realizedwhen the additive was employed in amounts from about 0.05 to 050 volumepercent of the fuel composition. The preferred concentration of theadditive is an amount from about 0.06 to 0.25 volume percent.

The test employed for testing the fuel compositions was the BuickInduction System Deposits Test conducted using a 1964 Buick 425 CID V-8engine. The fuels employed in the tests were evaluated basis depositratings of the intake valves and ports of the engine as more fullydescribed below.

The test is conducted using the noted engine equipped with a PCV(Positive Crankcase Ventilation) valve and installed on a dynamometertest stand with supporting equipment to control speed, load and enginetemperatures. This test requires approximately 350 gallons of fuel and 4gallons of lubricant per run.

Prior to each run, the cylinder heads are completely reconditioned andnew intake valves installed. Special care must be taken to insure thatthe inlet valve-tovalve guide clearance be maintained between 0.0035 to0.0045 inches. In addition, the valve seat widths are maintained between3/64 and 5/64 inches. The engine block is completely overhauled inaccordance with the procedures stated in the 1964 Buick Service Manualwhen blow-by or oil consumption become excessive.

The engine is charged with four quarts of oil and flushed for minutes at1500 rpm. Following an oil drain, four quarts of new oil are added andthe fuel tests begun. The engine is operated on a four-stage-six-hourcycle for a total of 16 cycles or 96 hours as follows:

-Continued State Cycle Time Hours Operation Temp.. F. Ckc's Oil 200 234t 2 234 i 2 Temp, F.

"Typical values, not controlled. "Approximate values-spark advance set6BTDC at 600 rpm.

Upon completion of a run, the cylinder heads and valves are removed andthe valves visually rated for the extent of deposit build-up on thevalve tulip surface. The intake valve deposits are rated according to amerit rating scale running from 10 to l. A rating of 10 indicates aperfectly clean valve while the rating of l is applied to an extremelyheavily coated valve. Deposits around the port opening are ratedT-trace, L-light, M- medium and H-heavy.

The following examples illustrate the practice of this invention. Theexamples give the characteristics of the mineral oil fraction which wasblended into the base gasoline to formulate the fuel composition of theinvention. The oils were blended with the base gasoline in theproportions indicated in volume percent basis the total fuelcomposition, the balance eing the base fuel.

The base fuel was a typical premium grade gasoline containing about 3cc. of tetraethyllead per gallon. This base fuel consisted of 25 percentaromatic, 14.5 percent olefinic and 60.5 percent aliphatic hydrocarbonsas determined by FIA analysis. This gasoline had an ASTM distillationIBP of F, an ER of 380F. and a Research Octane Number of about 101.3.

A typical commercial gasoline without the additive of the invention gavean intake valve rating of about 6.0 and a port rating of heavy. Animprovement in the valve rating of 0.5 units above the base fuel and anacceptable port rating, Trace of Light, is a significant improvement. Animprovement of 1 .0 unit or more generally to 7.0 or above and a passingport rating is a very substantial improvement in engine cleanliness.

EXAMPLE I.

A distillate paraffinic oil fraction of lubricating quality having anaverage molecular weight of 604, a 50 percent distillation point of1005F., and consisting of 64.1 percent paraffinic hydrocarbons and 3.8percent of aromatic hydrocarbons.

EXAMPLE 2.

The 50 percent bottoms from the distillation of the oil in Example 1having an average molecular weight of 670, a 50 percent distillationpoint of l050F. and consisting of 63.7 percent paraffinic hydrocarbonsand 4.9 percent aromatic hydrocarbons.

EXAMPLE 3.

A highly refined residual paraffmic oil fraction of lubricating qualityhaving an average molecular weight of 623, a 50 percent distillationpoint of 1026F., and consisting of 68.5 percent paraffinic hydrocarbonsand 6.2 percent aromatic hydrocarbons.

EXAMPLE 4.

A moderately refined residual paraffinic oil fraction of lubricatingquality having an average molecular weight of 670, a 50 percentdistillation point of 1042F., and consisting of 62.8 percent paraffinichydrocarbons and 8.4 percent aromatic hydrocarbons.

EXAMPLE 5.

A distillate paraffinic oil fraction of lubricating quality having anaverage molecular weight of 544. a 50 percent distillation point of967F.. and consisting of 63 percent paraffinic hydrocarbons and 3percent aromatic hydrocarbons.

EXAMPLE 6.

A highly refined residual paraffinic oil fraction of lubricating qualityhaving an average molecular weight of 712, a 50 percent distillationpoint of 1086F., and consisting of 70.5 percent paraffinic hydrocarbonsand 5.8 percent aromatic hydrocarbons.

EXAMPLE 7.

A highly refined residual paraffinic oil fraction of lubricating qualityhaving an average molecular weight of 734, a 50 percent distillationpoint of 1049F., and consisting of 66.7 percent of paraffmichydrocarbons and 4.1 percent of aromatic hydrocarbons.

EXAMPLE 8.

A moderately refined residual paraffinic oil fraction of lubricatingquality having an average molecular weight of 754, a 50 percentdistillation point of 1086F., and and consisting of 65.3 percent ofparaffinic hydrocarbons and 15.6 percent of aromatic hydrocarbons.

EXAMPLE 9.

A distillate naphthenic oil fraction of lubricating quality having anaverage molecular weight of 425, a 50 percent distillation point of857F.. and consisting of 44 percent paraffinic hydrocarbons and 19.5percent of aromatic hydrocarbons.

EXAMPLE 10.

A distillate paraffinic oil fraction of lubricating quality having anaverage molecular weight of 454, a 50 percent distillation point of865F., and consisting of 62.3 percent paraffinic hydrocarbons and 2.3percent of aromatic hydrocarbons.

EXAMPLE 11.

A distillate paraffinic oil fraction of lubricating quality having anaverage molecular weight of 430, a 50 percent distillation point ofabout 850F., and consisting of 61.6 percent paraffinic hydrocarbons and0 percent of aromatic hydrocarbons.

EXAMPLE 12.

A hydrotreated, cracked distillate oil fraction having an averagemolecular Weight of about 210, a 50 percent distillation point of 609F.,and consisting of 38.2 percent paraffinic hydrocarbons and 41.5 percentof aromatic hydrocarbons.

EXAMPLE 13.

Table 1 Buick Induction System Deposits Test Oil Concentration ValvePort Fuel Composition Vol. Percent Rating Rating Base fuel None 6.0 HExample 1 a 0.10 7.6 T b 0.16 7.8 T c 0.20 8.4 T d 0.32 9.0 T Example 20.16 8.7 T Example 3 a 0.50 9.0 L b 0.075 8.3 T c 0.15 8.5 L d 0.05 7.1L Example 4 0.50 9.0 L Example 5 0.50 7.6 L Example 6 0.16 9.0 T Example7 0.15 8.2 T Example 8 0.15 8.1 L Example 9 0.25 6.3 H Example 10 0.505.7 H Example 1 l 0.30 6.3 H Example 12 0.50 6.0 M Example 13 0.50 6.3 H

Examples 1 through 8, inclusive, are representative of the presentinvention and show surprising cleanliness of the engine intake valvesand ports in this test. The fuel compositions of Examples 9 through 13,which contain oils outside the specifically effective group. show littleor no improvement in this test or actually increased intake valve andport fouling.

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

We claim:

1. A motor fuel composition comprising a mixture of hydrocarbons in thegasoline boiling range containing from about 0.03 to 1.0 volume percentof a highly refined paraffinic oil fraction of lubricating oil qualityconsisting of 60 to 100 percent of paraffmic hydrocarbons and less than7 percent of aromatic hydrocarbons, said fraction having an averagemolecular weight in range of 600 to 800 and a 50 percent distillationpoint in a range of 950 to 1100F.

2. A motor fuel composition according to claim 1, containing from about0.05 to 0.5. volume percent of said paraffinic oil fraction.

3. A motor fuel composition according to claim 1 containing from about0.06 to 0.25 volume percent of said paraffmic oil fraction (and saidfraction consists of 60 to percent of paraffinic hydrocarbon).

4. A motor fuel composition according to claim 1 in which saidcomposition contains from (0.075) 0.06 to 0.25 volume percent of saidparaffmic oil fraction, said -fraction being characterized by consistingof 60 to 75 percent of paraffinic hydrocarbons and less than 7 percentof aromatic hydrocarbons having an average molecular weight in the rangeof 600 to 800 and having a 50 percent distillation point in the range of950 to l F).

5. A motor fuel composition according to claim 1, containing from about0.5 to 4.0 cc. of a tetraalkyllead antiknock compound per gallon.

6. A motor fuel composition according to claim 1 in which saidparaffinic oil portion has an average molecular weight of 604, a 50percent distillation point of 1005F and consists of 64.1 percentparaffmic hydrocarbons and 3.8 percent of aromatic hydrocarbons.

of hydrocarbons in the gasoline boiling range containing from about 0.03to 1.0 volume percent of a paraflinic oil fraction of lubricating oilquality consisting of 60 to percent of paraffinic hydrocarbons and lessthan 7 percent of aromatic hydrocarbons, said fraction having an averagemolecular weight in the range of 600 to 800 and a 50 percentdistillation point in a range of

1. A MOTOR FUEL COMPOSITION COMPRISING A MIXTURE OF HYDROCARBONS IN THEGASOLINE BOILING RANGE CONTAINING FROM ABOUT 0.03 TO 1.0 VOLUME PERCENTOF A HIGHLY REFINED PARAFFINIC OIL FRACTION OF LUBRICATING OIL QUANTITYCONSISTING OF 60 TO 100 PERCENT OF PARAFFINIC HYDROCARBONS AND LESS THAN7 PERCENT AROMATIC HYDROCARBONS, SAID FRACTION HAVING AN AVERAGEMOLECULAR WEIGHT IN THE RANGE OF 600 TO 800 AND A 50 PERCENTDISTILLATION POINT IN THE RANGE OF 950* TO 1100*F.
 2. A motor fuelcomposition according to claim 1, containing from about 0.05 tO 0.5.volume percent of said paraffinic oil fraction.
 3. A motor fuelcomposition according to claim 1 containing from about 0.06 to 0.25volume percent of said paraffinic oil fraction (and said fractionconsists of 60 to 75 percent of paraffinic hydrocarbon).
 4. A motor fuelcomposition according to claim 1 in which said composition contains from(0.075) 0.06 to 0.25 volume percent of said paraffinic oil fraction,said fraction being characterized by consisting of 60 to 75 percent ofparaffinic hydrocarbons and less than 7 percent of aromatic hydrocarbons(, having an average molecular weight in the range of 600 to 800 andhaving a 50 percent distillation point in the range of 950* to 1100*F).5. A motor fuel composition according to claim 1, containing from about0.5 to 4.0 cc. of a tetraalkyllead antiknock compound per gallon.
 6. Amotor fuel composition according to claim 1 in which said paraffinic oilportion has an average molecular weight of 604, a 50 percentdistillation point of 1005*F and consists of 64.1 percent paraffinichydrocarbons and 3.8 percent of aromatic hydrocarbons.
 7. A motor fuelcomposition according to claim 1 in which said paraffinic oil fractionhas an average molecular weight of 670, a 50 percent distillation pointof 1050*F and consists of 63.7 percent paraffins and 4.9 percentaromatic hydrocarbons.
 8. A method for preventing the build up of intakevalve and port deposits in a four-cycle internal combustion gasolineengine which comprises supplying to said engine a motor fuel compositioncomprising a mixture of hydrocarbons in the gasoline boiling rangecontaining from about 0.03 to 1.0 volume percent of a paraffinic oilfraction of lubricating oil quality consisting of 60 to 100 percent ofparaffinic hydrocarbons and less than 7 percent of aromatichydrocarbons, said fraction having an average molecular weight in therange of 600 to 800 and a 50 percent distillation point in a range of950* to 1100*F.